Electrical connectors having terminals, such as for making releasable electrical connection to electrical conductors of a communications network, may be arranged to receive over-voltage protection devices which, in the event of an over-voltage condition on a conductor, act to provide a conductive path to ground. Such devices may be connected across respective pairs of conductors associated with respective communications circuits. Each over-voltage device may comprise a three terminal device, first and third terminals of which are in use connected to respective conductors of the pair with which it is associated. The second terminal is connected to ground. Under the condition of normal voltage across such a device, the device presents a high impedance as between all terminals, but under over-voltage conditions on either the first or second terminals, breakdown occurs to provide a conductive path from the terminal exhibiting the over-voltage to ground (earth). The provision of devices of this type is important in practical communications systems to prevent over-voltage conditions, arising for example from lightning strikes, from causing serious damage to the system.
Practically, in for example a telephone exchange, the connectors which releasably connect to the network conductors are arranged on suitable support structure with the terminals facing outwardly for ease of access, bearing in mind that alterations to the connections from the connector terminals to the conductors may need to be frequently made, to accommodate the needs of network users. In such a construction, the over-voltage protection devices may then be mounted to the fronts of the connectors. This mounting arrangement is convenient from the point of view of ease of access, since the over-voltage devices themselves may need to be accessed for replacement. However, mounting these in this fashion is also inconvenient in that the devices are then adjacent the connector terminals and inhibit convenient access to the connector terminals.